Octanitroterphenyl

ABSTRACT

A NEW EXPLOSIVE COMPOUND OF 2,2&#34;,4,4&#39;&#39;,4&#34;,6,6&#39;&#39;,6&#34;-OCTANITRO-M-TERPHENYL AND METHODS FOR PREPARING IT.

United States Patent 3,592,860 OCTANITROTERPHENYL Joseph C. Dacons, Washington, D.C., assignor to the United States of America as represented by the Secretar of the Navy. No Drawing. Filed Nov. 22, 1967, Ser. No. 685,736 Int. Cl. C07c 79/10 US. Cl. 260645 9 Claims ABSTRACT OF THE DISCLOSURE A new explosive compound of 2,2",4,4',4:',6,6,6"-octanitro-m-terphenyl and methods for preparing it.

BACKGROUND OF THE INVENTION This invention generally relates to high explosive aromatic nitro compounds and, more particularly, to 2,2",4,4',4",6,6,6"-octanitro-m-terphenyl and its method of preparation.

Modern missile and space advances have indicated a definite need for thermally stable explosives which are, nevertheless, sensitive to impact and capable of delivermg a large output of energy. As disclosed in appl1cant s application, Ser. No. 320,579, filed on *Oct. 31, 1963, it has been found that certain polynitropolyphenyl explosives, for example, 2,2',2",4,4',4",6,6,6"-nonanitroter phenyl (hereinafter known as NONA) exhibit desired properties of thermal stability and impact sensitivity. However, it was hoped that other polynitropolyphenyl compounds would exhibit even better explosive properties than those shown by NONA. Further, it was desired to use a process of preparation which would yield the explosive in good amounts, thus providing minimal productlon costs.

SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to supply an explosive compound having high thermal stability and impact sensitivity.

Another object of this invention is to provide a novel polynitropolyphenyl compound of 2,2",4,4,4",6,6',6-octanitro-m-terphenyl, hereinafter known as ONT.

Still another object of this invention is to furnish a method of preparation which yields ONT in good amounts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polynitropolyphenyls of the invention are prepared by the reaction of picryl halides and a dihalodinitrobenzene in the presence of a copper catalyst and an inert diluent. Picryl halides which may be used are exemplified by picryl chloride, picryl bromide and picryl iodide. Halodinitrobenzenes which may be employed are exemplified by 1,5-dibromo-2,4-dinitrobenzene, and the corresponding dichloro and diiodo compounds. The reaction may involve compounds having the same or different halogens. For example, picryl chloride may be reacted with 1,5-dibromo- 2,4-dinitrobenzene or either one or both of the compounds may have chlorine, bromine or iodine as the halogen substituent. The rates of reaction and yields of products will, of course, vary depending on the particular halogens utilized in the reacting compounds.

The copper catalyst consists of different forms of finely divided copper such as mechanically pulverized copper (copper bronze) which may be treated by successive washing with acetone solutions of iodine and hydrochloric acid. Another form which may be used is lithographic bronze which contains 0.2-0.5% fatty acids.

The picryl halide and the halodinitrobenzene are reacted under anhydrous conditions in the presence of finely divided copper in any high boiling organic diluent which is inert to the reaction. Illustrative diluents are mononitrobenzene, toluene, dimethylformamide and nitrotoluene. It is important that the reaction mixture be kept anhydrous to avoid dehalogenation of the starting materials. The reaction may be carried out under subnormal, normal or supernormal atmospheric conditions and at temperatures ranging from about C. to the boiling point of the diluent. Preferably, however, the reaction is carried out at normal atmospheric presure and at the lowest practicable temperature.

ONT may also be prepared by the nitration of 2,2",4,4",6,6-hexanitroterphenyl using either mixtures of nitric and sulfuric acids or alkali nitrates in oleum.

The following examples are intended to illustrate methods of preparation of ONT, which utilize several characteristic reactants, however, these examples are not intended in any way to limit the scope of the invention.

EXAMPLE I The preparation of 1,S-dibromo-Z,4-dinitrobenzene. To a mixture of 200 ml. of cone. sulfuric and 200 ml. of 90% nitric acids in a 1000 ml. 3-neck round bottom flask fitted with a mechanical stirrer and thermometer cooled on an ice bath was added 200 g. (0.85 mole) of m-dibromobenzene. The mixture was stirred throughout the reaction and the addition was at such a rate as to keep the temperature from rising above 50 C. Precipitation occurred soon after the addition started. When the addition was complete and the temperature had dropped to 35 C., the ice bath was removed and stirring continued for two hours. The reaction mixture was then drowned in an excess of crushed ice, filtered through a sintered glass funnel and the product was washed with water until the washings were neutral. After drying in a warm oven, the crude product weighed 275 g. It was dissolved in 1000 m1. of boiling methanol, the solution Was filtered and cooled on an ice bath. A bright yellow crystalline product formed. It was recovered by filtration, Washed with 200 ml. of 65% methanol, and after drying, weighed 169.3 g. and melted at 1l41l6 C. The filtrate and washings were concentrated to a volume of ca. 950 ml., cooled on an ice bath, filtered and the product was washed with 50 ml. of 65 methanol. After drying, the second crop, M.P. 109-- 112 C., weighed 28.5 g. By again concentrating the filtrate and washings to a volume of ca. 800 ml., cooling on a ice bath and filtering, a third crop of 45.6 g. M.P. 65- 70 C., was obtained. The third crop was recrystallized from 200 ml. of methanol giving 8.3 g. of bright yellow crystals, M.P. 1121l5 C., and resembling those of crops one and two. The total yield of crude 1,5-dibrom0- 2,4-dinitrobenzene, M.P. 109-116 C., was 206.1 g. (74.4%

The crude product was dissolved in 425 ml. of hot carbon tetrachloride, filtered and cooled in the refrigerator. On filtration, a yield of 194.0 g. (70%) of pure 1,5-dibromo-2,4-dinitrobenzene, M.P. 1l6-7 C. (Litt. 117 C.), was obtained.

EXAMPLE II Preparation of ONT from 1,S-dibromo-2,4-dinitrobenzene and picryl chloride.-A slurry of 44.0 g. (0.7 mole) of copper bronze in ml. of dry nitrobenzene was made in a 1000 ml. 3-neck round bottom flask fitted with a mechanical stirrer, a thermometer and an addition funnel. The temperature of the slurry was raised to C. on an oil bath supported by a laboratory jack. A solution of 65 g. (0.25 mole) of picryl chloride and 32.6 g. of 1,5-dibromo-2,4-dinitrobenzene in 150 ml. of dry nitrobenzene was placed in the addition funnel and a volume of 25 ml. was added to the hot copper slurry with vigorous stirring.

3 After five minutes, reaction was obvious as the copper had lost some of its luster, the mixture had begun to darken and the temperature had risen to 175 C. The heating bath was then lowered and when the temperature had fallen below 170 C., the remainder of the solution was added in a slow stream. The temperature was kept at 165170 C. during the remainder of the addition period (about 10 minutes) by controlling the rate of addition and the height of the heating bath. The reaction mixture was kept at this temperature for an additional 10 minutes then allowed to cool to about 120 C. A volume of 300 ml. of toluene was then added and the mixture was cooled on an ice bath and filtered. The residue was washed with toluene until nearly colorless then with methanol until again nearly colorless. It was then heated in 600 ml. of 20% hydrochloric acid with stirring for about 10 minutes to remove the inorganic copper salts. The residue, which at this point contained mainly ONT with a small amount of unused copper, was recovered by filtration,

washed with dilute hydrochloric acid, water and finally methanol. It was then dissolved in 400 ml. of dimethylsulfoxide, DMSO, giving a very dark solution which was treated with 20 g. of Darco G60, filtered with suction through a glass fiber filter paper and the solution was again filtered through fiber glass filter paper to remove last traces of insolubles. To the warm solution was added slowly 600 ml. of methanol with stirring upon which crystallization occurred. After cooling in the refrigerator overnight, the cream colored crystalline ONT was recovered by filtration, thoroughly washed with methanol and dried in the oven at 100 C. The yield at this point was 45.0 g. (76% It was dissolved in 700 ml. of nitrobenzene at its boiling point and cooled slowly, first on the hot plate then on the bench. A yield of 43.2 g. (73%) of bright yellow crystalline ONT was recovered by filtering through sintered glass, thoroughly washing with methanol and drying at 140 C. under reduced pressure for 16 hours. The product showed no tendency to melt at 400 C. and was chromatographically identical to that prepared by the nitration of 2,2".4.-1".6.6"-hexanitro-m-terphenyl. See Example VII. X-ray diffraction patterns of the two products were also identical.

X-ray molecular weight determination. Calcd. for C13H6N3O16: Found:

EXAMPLE III Preparation of ONT from 1,5-dibromo-2,4-dinitrobenzene and picryl bromide-A slurry of 1 1.1 g. (0.16 mole) of copper powder 1 in 50 ml. of dry nitrobenzene was made in a 300 ml. 3-neck round bottom flask fitted with a mechanical stirrer, a thermometer and an addition funnel. The temperature of the slurry was raised to 135 C. on an oil bath supported by a laboratory jack. A solution of 12.6 g. (0.043 mole) of picryl bromide and 6.3 g. (0.017 mole) of 1,5-dibromo-2,4-c1initrobenzene in 50 ml. of dry nitrobenzene was placed in the addition funnel and a volume of 5 ml. was added to the copper slurry with vigorous stirring. After about five minutes, reaction was obvious as the copper had lost some of its luster, the mixture had begun to darken and the temperature had risen to 140 C. The temperature was then maintained at 135 140 C. as the remainder of the solution was added (about minutes). The mixture was kept at this temperature for an additional minutes and allowed to cool to about 120 C. It was then poured into 250 ml. of toluene, cooled on an ice bath and filtered. The residue was washed thoroughly with toluene and the ONT (from DMSO- Methanol) was isolated as described in the picryl chloride-1,S-dibromo-Z,4-dinitrobenzene synthesis, the volume of reagents being reduced accordingly. The yield was 5.0 g. (50%).

EXAMPLE IV Preparation of ONT from 1,S-dibromo-2,4-dinitroben- Matheson Coleman and Bell purified copper powder.

4 zene and picryl iodide.The preparation was identical to Example 111 except that 14.6 g. (0.043 mole) of picryl iodide was used instead of picryl bromide. The yield was 5.6 g. (56%).

EXAMPLE V Preparation of ONT from 1,5-dichloro-2,4-dinitrobenzene and picryl chloride-The procedure was identical to Example 111 above except that 4.0 g. (0.017 mole) of 1,5-dichloro-2,4-dinitrobenzene and 10.6 g. (0.043 mole) of picryl chloride were used as the organic reactants and the reaction temperature range was 188-200" C. The yield was 0.6 g. (6.0%).

EXAMPLE VI Preparation of 2,2,4,4",6,6"-hexanitro-m-terphenyl. A slurry containing 12.0 g. (0.05 mole) of m-dibromobenzene, g. (0.32 mole) of copper bronze and ml. of dry nitrobenzene was made in a 200 ml. 3-neck round bottom flask fitted with a mechanical stirrer and thermometer. A solution of 29.5 g. (0.12 mole) of picryl chloride in m1. of dry nitrobenzene was made and placed in an addition funnel. The slurry was heated to 140 C. on an oil bath while stirring vigorously. A volume of about 10 ml. of the picryl chloride solution was added and the temperature was raised to 160 C. over a 10 minute period. The mixture had begun to darken and the remainder of the picryl chloride solution was added over an additional 10 minute period during which the temperature was kept at 160-165" C. Heating was continued for 15 minutes after the addition was complete, then the thick mixture was cooled, diluted with acetone, filtered and the residue thoroughly washed with acetone. The solvent was then removed by steam distillation and the residue was digested for 15 minutes in boiling methanol. After the methanol was removed by decantation, the residue was dissolved in 600 ml. of hot acetone, treated with 10 g. of Darco 6-60, and filtered with suction through glass fiber paper giving a light yellow filtrate. The copper residue from the initial filtration was extracted with 500 ml. of boiling acetone, and the extract was filtered through a pad of Darco G giving a light yellow filtrate as above. The two filtrates were combined and concentrated to a volume of approximatelly 250 ml. by distillation. A volume of 250 ml. of toluene was then added and distillation continued until appreciable precipitation had occurred and the vapor temperature was C. The precipitate was recovered by filtration, washed with toluene and dried at C. The light yellow finely crystalline product weighed 20.6 g. (82.4%) and melted at 290-4" C. A l g. sample was dissolved in 80 ml. of boiling acetone, filtered and 50 ml. of acetic acid was added. The acetone was then removed by distillation during which fine pale yellow crystals formed. The product was recov ered by filtration, washed with ether and after drying at C., it melted at 294-6 C.

Analysis.Calcd. for C H N O (percent): C, 43.32; H, 1.61: N. 16.80. Found (percent): C, 43.42, 43.68; H, 1.68, 1.71; N, 17.24, 16.95.

EXAMPLE VII Preparation of ONT by nitration.To a solution of 12 g. of potassium nitrate in 30 m1. of 30% oleum in a 100 ml. 3-neck round bottom flask fitted with a mechanical stirrer and thermometer, was added 9.5 g. (0.019 mole) of 2,2,4,4",6,6"-hexanitro-m-terphenyl at room temperature. The reaction flask was fitted with a condenser and the mixture was heated to 127 C. with stirring on an oil bath for 22 hours. It was then cooled and drowned in an excess of crushed ice. The product was recovered by filtration, thoroughly washed with water and dried in a warm oven. The yield was 10.4 g. of a finely divided faintly yellow product. An acetone solution of this material was spotted on a thin-layer chromatographic plate coated with Silica Gel G and developed with a solution of benzene-ethanol 75: 1. When the zones were visualized by spraying with a saturated solution of alcoholic potassium hydroxide, it was evident that the product was a mixture of at least five components (three major and two minor). The product was suspended in 500 ml. of acetone, the suspension was brought to boil then allowed to cool. The insoluble portion was recovered by filtration and, when dried, weighed 4.0 g. It did not melt at 360 C. and, when chromatographed as above, showed a single spot at the origin. This product was recrystallized by dissolving in 75 ml. of boiling nitrobenzene and cooling slowly. It was recovered by filtration, washed first with cold nitrobenzene then with toluene and dried in a vacuum oven at 140 C. for 16 hours. The glistening yellow crystals weighed 3.5 g. (30% yield) showed no tendency to melt at 360 C. and when chromatographed as above using benzene-acetone :1 as developer, showed a single spot, R,=0.59.

Analysis.Calcd. for C H N 0 (percent): C, 36.65; H, 1.02; N, 18.98. Found (percent): C, 37.01, 36.92; H, 0.94, 0.98; N, 18.17, 18.07.

The novel compound ONT was found to have properties which indicate that it can function well as an explosive at very high temperatures. Tests show that ONT is capable of working at temperatures of approximately 20 C. higher than NONA and yet it exhibits higher impact sensitivity than NONA (64 cm. compared with 37 cm.). These properties do not seem to effect the output of ONT, which preliminary tests indicate is not appreciably different from that of NONA.

Because of its crystal size and shape, ONT in addition may be elfectively used in high temperature plastic bonded explosives. Other possible areas of use also include mild detonating fuzes in missiles and airplane applications and thermally stable booster explosive compositions.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. The compound 2,2",4,4',4",6,6',6" octanitroterphenyl.

2. The method of preparing the compound of claim 1 which comprises reacting a picryl halide with a dihalodinitrobenzene under anhydrous conditions in the presence of an inert diluent and finely divided copper.

3. The method of claim 2 wherein the dihalodinitrobenzene is 1,5-dibromo-2,4-dinitrobenzene.

4. The method of claim 3 wherein the picryl halide is picryl chloride.

5. The method of claim 3 wherein the picryl halide is picryl bromide.

6. The method of claim 3 wherein the picryl halide is picryl iodide.

7. The method of claim 2 wherein the dihalodinitrobenzene is 1,5-dichloro-2,4-dinitrobenzene and the picryl halide is picryl chloride.

8. The method of preparing the compound of claim 1 which comprises nitrating 2,2,4,4',6,6--hexanitro-mterphenyl.

9. The method of claim 8 wherein the nitration is accomplished by an oleum alkali nitrate solution.

References Cited UNITED STATES PATENTS 5/ 1967 Kamlet et al. 149-105X 9/1968 Nilsson et a1 260645X OTHER REFERENCES Fanta, Chem. Reviews, vol. 64, pp. 613 to 625 (1964). 

